Moisture Simulation Model for Polymer Composites

1. Moisture Simulation Model for Polymer Composites B.C.=SATURATION Student(s): Zhen Huo Mechanical & Aerospace Engineering Department Faculty Advisor(s): Dr. K. Chandrashekhara, Mech. & Aero. Engineering Dept. Dr. Thomas Schuman, Chemistry Dept. X=0 X=1.7703 mm • OBJECTIVES • Develop 3D finite element model for moisture absorption of fiber-reinforced polymer composites. • Perform case studies for glass fiber-reinforced polymer composites over long time periods. • Validate the simulation results with the analytical and experimental results. FINITE ELEMENT MODELING & SIMULATION Variance Study Face B.C. is applied ABAQUS 3D half modeling ABAQUS 2D half modeling Convergence study with half modeling after 168 soaking hours Aspect ratio effects study with half modeling using 50 nodes mesh FINITE ELEMENT RESULTS INTRODUCTION VALIDATION • Composite materials degrade due to environmental exposure such as moisture diffusion, thermal spike, UV, and thermal oxidation. • Moisture absorption of composites decreases the strength and stiffness, degrade the fiber/matrix interface strength, swell and plasticize the resin lowering its glass transition temperature. • The relative degree of degradation is related to chemistry of the reinforcement and matrix as well as the exposure time. • The determination of moisture concentration profile through the thickness of the composite structure requires the knowledge of 3D moisture diffusion coefficients. 3D half modeling moisture content results comparison after 168 hours 2D half modeling moisture content results comparison after 168 hours Abaqus 2D half modeling moisture content after 168 hours • Governing Equations • CONCLUSIONS AND FUTURE WORK • Simulation results match well with 1D analytical results, which validates the finite element model. • Results are presented for both 2D and 3D models. • Study polymer composites moisture evolution under complex environments. • Evaluate the effects of temperature and humidity on polymer composites moisture behavior subjected to long time exposure. FINITE ELEMENT RESULTS (Cont. ) where c is moisture concentration, t is time span, n is outward normal to S. J is concentration flux and is given by: where s is solubility, ∅ is the normalized concentration, which equals c/s, ks is “soreteffect” factor, providing temperature gradient driven diffusion; kpis the pressure stress factor, providing pressure gradient driven diffusion; θzis absolute zero temperature. Acknowledgements This project is funded by Bell Helicopter Inc. and Intelligent Systems Center. Abaqus 3D half modeling moisture content after 168 hours D11= 4.44158E-5 mm2/h; D22= D11 / 2; D33 = D11 / 4